An electric vehicle powered by an electric motor and a hybrid electric vehicle powered by a combustion engine and an electric motor incorporate a power supply apparatus as a source for driving the electric motor. The power supply apparatus includes a battery cell assembly constructed by a plurality of battery cells each having a positive electrode at one end and a negative electrode at the other end, the battery cells being series-connected with each other to obtain a desired voltage. These battery cells are arranged in one direction and juxtaposed to each other.
It is often the case with the power supply apparatus of this sort that the positive electrode of one of a mutually adjacent pair of the battery cells that belong to the battery cell assembly is connected via a connecting member to the negative electrode of the other of the pair of the battery cells so that the battery cells are connected to construct the battery cell assembly. The use of such connecting members attached to the battery cell assembly needs troublesome process for assembling the power supply apparatus.
To address the aforementioned problem, as an example, a busbar module is advocated that is capable of attaching the connecting members en bloc to the battery cell assembly, the connecting members used to connect the battery cells in series with each other (for example, see the patent literature PTL 1). The busbar module described in the patent literature PTL 1 includes: a plurality of bus bars serving as the connecting members for series-connecting the battery cells to construct the battery cell assembly; a plurality of electric wires for voltage detection detecting voltage of corresponding each of the battery cells, the electric wires each having a terminal attached to its end and used to connect the electric wires to each of the bus bars; and a plate with the bus bars and the electric wires for voltage detection attached thereto, the plate adapted to be mounted to the battery cell assembly.
The bus bars may be made of electrically conductive metal material in a shape of a strip having holes for passing therethrough the positive and negative electrodes. The electric wires for voltage detection are known sheathed electric wires that include an electrically conductive core wire and insulating sheath covering the core wire. The terminal is attached to its end. The terminal includes an electrode connecting part piled on the bus bar and having a hole through which the electrode is passed and an electric wire connecting part configured to be connected to the electric wire.
The plate is made of synthetic resin, whose planar shape takes the shape of a rectangular flat plate. The plate includes: a plate body having a plurality of holes provided therein for passing the positive and negative electrodes therethrough; a plurality of busbar-accommodation portions arranged on a surface of the plate body in a direction in which the battery cells are arranged, the busbar-accommodation portions being constructed to accommodate the bus bars and terminals connected to each of the bus bars; a plurality of electric wire holding portions holding the voltage-detecting electric wires disposed therein; and a cover provided on the plate body by means of a hinge. Also, the plate includes an accommodating groove positioning therein one electrical wire extending from an end of the plate body, the one electrical wire being connected to an electrode taking out a voltage of the series-connected battery cells and configured to output the voltage to an external device.
In the aforementioned busbar module, the plate including the bus bars and the terminals that are attached to each of the bus bar accommodating portions is disposed upon the surface of the battery cell assembly on which the electrode is provided. Further, the electrodes of the battery cells are passed through each of the holes of the plate body and holes of the bus bar and the terminal. After that, nuts are screwed onto the electrodes of the battery cells. In this manner, the bus bars are attached to the battery cell assembly with the battery cells connected in series with each other via the bus bars.
The voltage-detecting electric wires connected to each of the terminals are positioned inward of each of the electric wire holding portions, the one electrical wire connected to the electrode for taking out the voltage of the series-connected battery cells of the battery cell assembly is positioned inward of the accommodating groove provided in the plate of the busbar module, and thus the voltage-detecting electric wires and the one electrical wire are secured to the busbar module. Further, another electrical wire is connected to another electrode adapted to take out the voltage of the series-connected battery cells.
In this manner, the aforementioned busbar module, with the plate to which the bus bars and the terminals are attached is mounted to the battery cell assembly, so that the bus bars is used to connect the battery cells of the battery cell assembly in series with each other, and each of the terminal attached to each of the voltage-detecting electric wires can be connected to each of the battery cell of the battery cell assembly, thereby the operation of installation to the battery cell assembly is facilitated.